U.S. patent number 4,133,542 [Application Number 05/719,086] was granted by the patent office on 1979-01-09 for spring seal.
Invention is credited to Rolla J. Boyer, Robert Janian.
United States Patent |
4,133,542 |
Janian , et al. |
January 9, 1979 |
Spring seal
Abstract
A seal comprising a spring having an enlarged diameter base
mounted in the heel of a seal casing to enable flared arms
extending forwardly from the base to freely exert by cantilever
action an outwardly directed spring bias against the casing while
the spring is retained by its base in the casing.
Inventors: |
Janian; Robert (N. Hollywood,
CA), Boyer; Rolla J. (Whittier, CA) |
Family
ID: |
24888701 |
Appl.
No.: |
05/719,086 |
Filed: |
August 31, 1976 |
Current U.S.
Class: |
277/555 |
Current CPC
Class: |
F16J
15/3212 (20130101); F16J 15/3208 (20130101) |
Current International
Class: |
F16J
15/32 (20060101); F16J 009/06 (); F16J
015/32 () |
Field of
Search: |
;277/152,205,164,157,162,138 ;267/1.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Aegerter; Richard E.
Assistant Examiner: Footland; L.
Attorney, Agent or Firm: Romney, Schaap, Golant, Scillieri,
Disner & Ashen
Claims
We claim as our invention:
1. A sealing device comprising:
a unitary spring member including a base with a first diameter and
having a convex surface extending fully around its exterior, and
further including a pair of opposite arms together having a
generally V-shaped cross section and rearwardly connected to said
base through a narrow neck having a second diameter less than said
first diameter and with forwardly divergent free ends normally
separated a third distance greater than said first diameter;
and
a casing in contact with a sealing surface and including a channel
for receiving said spring, said channel having a heel formed at the
rear of said channel by concave end wall means extending fully
around said heel for snugly abutting said exterior convex surface
of said spring base, and further having an entrance passage formed
at the front of said channel by forwardly divergent side wall means
for snugly abutting the outside surface of said spring arms leaving
said spring arms free of any circumferential constraint directed
rearwardly against said forward ends of said spring arms, and
further having constricted junction means between said end wall
means and said side wall means for engaging said neck to securely
hold said base of said spring in cantilever fashion in said heel of
said casing while enabling the forward end of said spring arms to
flex freely exerting a lateral sealing force against said side
walls of said casing.
Description
FIELD OF THE INVENTION
This invention relates to mechanical seals generally, and more
particularly to cover seals of various materials having inner
springs to provide the necessary resiliency for sealing the passage
between two adjacent surfaces.
BACKGROUND OF THE INVENTION
In the past, conventional springs mounted in a sealing jacket or
casing have often lost their resilient sealing capabilities when
subjected to repeated use under extreme pressures and temperatures.
It is believed that such failures have been caused by poor
construction features of the spring/cover combination whereby the
forward flexing ends of the spring are held in fixed longitudinal
position by the overlapping forward lips of the cover while the
central spring leg moves back and forth in the inner cavity of the
cover to accomodate the lateral flexing of the spring. Such prior
art structure results in bad performance by both the spring and the
cover or jacket. Such prior art seal/cover combinations have
therefore failed to provide continuous reliable sealing along a
smooth evenly loaded sealing surface over extended periods of
time.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved
spring/casing combination which overcomes the deficiencies of the
prior art. To this end, an improved spring is formed from a single
strip of metal to provide a plurality of opposing flared arms each
extending from an enlarged concave base. The casing is machined out
to provide a heel portion for fixedly mounting the base thus
allowing the arms to extend outwardly for lateral flexing of the
arms as cantilevers extending from the fixed base. The sealing lips
portion of the casing is biased outwardly by the inner spring
flexing of the arms while still leaving the arms to freely move
relative to the casing.
Additional purposes, objects, features and advantages of the
invention will be evident to those skilled in the art from the
following description of exemplary embodiments of the
invention.
DRAWING
In the drawings:
FIG. 1 is a perspective view of a presently preferred form of
spring;
FIG. 2 is a sectional view of a modified spring mounted in a
casing;
FIG. 3 is a sectional view of the spring of FIG. 1 mounted in a
casing;
FIG. 4 is a sectional view of the spring/casing combination of FIG.
3 in sealing engagement between two surfaces;
FIG. 5 is a sectional view of the spring of FIG. 1 mounted in a
modified casing;
FIG. 6A shows the spring of FIG. 1 in circular form with the flared
arms pointing inward for use in a face seal
FIG. 6B shows the spring of FIG. 1 in circular form with the flared
arms pointing outward for use in a face seal;
FIG. 6C shows the spring of FIG. 1 in circular form with the flared
arms pointing up from the plane of the paper for used in an inside
or outside diameter radial seal;
FIG. 7 shows a spring strip of the type shown in FIG. 1 in various
stages of manufacture;
FIG. 8 is a top view in partial section showing a spring strip
being punched by an exemplary slotting die;
FIG. 9 is an end view taken along the line 9--9 in FIG. 8;
FIG. 10 is a top view showing a slotted spring strip being dimpled
by an exemplary shaping die;
FIG. 11 is an end view taken along the line 11--11 in FIG. 10;
FIG. 12 is a top view showing a slotted, dimpled spring strip being
contracted together by a different exemplary shaping die; and
FIG. 13 is an end view taken along line 13--13 in FIG. 12.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, the preferred form of the spring 20
includes opposing first and second arm members 21, 22 extending
outwardly from a base 23 which is preferably an enlarged concave
shape which joins through first and second junctions 24, 25 to the
respective arm members.
As best shown in the sectional views of FIGS. 3 and 4, the enlarged
diameter defined by the outer surface 26 of the base is engageable
with the portion of a casing or cover 40 having a heel 41 which
snugly fits against the outer junction surfaces 27 to hold the base
of the spring in fixed position in the casing with the arms free to
move relative to the casing as the load forces the spring biased
arms to change position. This enables the outer arm surfaces 28 to
be in continuous abutting contact with the surrounding casing along
the full length of the arm to facilitate the transfer of even,
constant pressure from the spring biased arms through the casing to
its sealing lips 42.
In order to provide sealing along an elongated junction, an
elongated spring assembly as shown in FIG. 1 is provided having
slots 29 between adjacent arms, with the slots protruding
alternately from the exterior of the spring to connectors 30, 31
which hold adjacent arms together. Thus, the spring force is
transmitted by cantilever action from the base through the arms to
the tips 32 on the forward edges 32 of the connectors to provide
the spring force in the outward direction shown by the arrow 33.
(See FIG. 4).
In an alternate construction for a spring 20a, as shown in FIG. 2,
it is possible to have separate spring members with divergent bases
23a in the rear of the casing to hold the spring in position by the
constricting action of the casing against the inwardly bent
junctions 24a, 25a between the base and the arms.
Of course, the spring is suitable for mounting in other forms of
jackets such as shhown in FIG. 5 wherein an abbreviated cup 43
carries a sealing material 44 which serves to hold the base of the
spring in fixed position while the spring arms move freely to exert
outward spring bias against the sealing lips 45, which may where
desirable extend beyond the forward ends of the spring arms.
However, as best shown in FIG. 4, in the preferred embodiment, the
heel is typically designed for insertion in a groove 50 which
serves as a gland formed between two opposing surfaces 52, 53 to
receive the seal unit and prevent passage of fluid or the like in
the longitudinal direction shown by the double arrow 51. Under such
circumstances, it was found preferable to have the outer shape of
the cover 40 conform to the shape of the groove, with the ends of
the spring arms and the cover substantially coincident thus
providing a sealed joint without the need for any additional
sealing material other than the jacket or cover itself, with its
resilient memory provided by the spring.
The shape of the spring is important to provide proper mounting in
the heel of the casing as well as to provide maximum outward spring
bias of the arms when subjected to a load. Although a progressive
die system can be used to punch and then shape a strip of metal
from initial stages shown at 60 to a completed spring shown at 61,
in FIG. 7, an optimum system was developed with a minimum number of
steps and tooling, as shown in FIGS. 8-13.
More specifically, a base is formed by impressing a concave
depression in the form of two downward dimpled recesses 70, 71 with
a transverse ridge or hump 72 therebetween while holding the spring
arms 73 in aligned horizontal position. The hump can then be pushed
downwardly to draw the surrounding concave depression upwardly to
form a cross-sectional loop shape having flared arms 74 extending
from an enlarged concave base 75.
Where an elongated spring is made, the strip is first punched with
lateral slots 76 to form the plurality of lateral arms 77
alternately connected through end members 78. The aforementioned
shaping steps are then performed sequentially on each lateral
arm.
The aforementioned structure can then be rotated about its base for
sealing directed in any direction (See FIGS. 6A, 6B, and 6C).
Accordingly, in view of the foregoing description, it will be
appreciated by those skilled in the art that the invention provides
a unique spring/cover combination wherein the flexible spring arms
and the surrounding cover are in substantial alignment,
notwithstanding the degree of flexing caused by the load being
carried by the seal lips of the casing. Similarly, in the preferred
form, the forward end of the arms is substantially coincidental
with the forward end of the seal lips of the casing, thereby
eliminating either spring or cover protrusion. This alignment
between the cover and the spring is maintained and controlled by
the use of a unique base seated in the heel of the casing. Also, if
for some reason the spring base is removed from the heel, it can be
reinserted, so that when the casing/spring insert is placed in the
gland between the two adjacent surfaces and subjected to a load,
the compression of the opposing spring seals automatically locks
the base of the spring in the matching seat or groove in the heel
of the casing.
Moreover, by leaving the forward ends of the spring arms free from
any longitudinal, forward restraint, the seal cover can be machined
to fit snugly into mating relationship with the entire outside
surface of the spring, thus preventing undesirable twisting or
bulging behind the sealing surfaces during operation. Such
construction in many instances virtually eliminates the need for
conventional back-up rings. This also leaves the forward spring arm
ends which have the maximum flexing displacement capability in
direct contact with the forward ends of the seal lips, providing a
positive seal along the preferred sealing surface of the cover.
Additionally, by providing a work hardened base for the spring, it
is possible to achieve more resiliency in the actual sealing area
of the casing. As described previously, such work hardening occurs
during the various steps of the forming operation as shown in FIGS.
8 through 13.
Openings and gaps between the various adjacent surfaces of the
spring/casing combination are avoided, thus providing a smooth
loading surface maintained by the cantilever spring action of the
arms impelled outwardly by the enlarged concave base of the spring.
Thus, continuous loading is transmitted from the spring base
through the outwardly biased arms to the sealing surfaces along the
edges of the seal lips of the casing.
Additionally, elimination of the usual cavity at the rear of the
casing enables use of a jacket or casing of reduced overall
thickness, thus preventing the jacket from over-restraining the
resilient action of the spring.
Because of the unique spring features of the invention, various
cover materials can be used, including Teflon, Kel-F, FEP, Kynar,
polimides and filled fluorocarbon compounds. In addition,
elastomers such as viton, Buna, silicones, and the like which
require a low stress deflection ratio are also available. The
elastomeric life of the cover is thereby increased due to the
constant pressure being exerted on the sealing surfaces even though
the elastomers themselves may become embrittled as a result of
operational use. The unique structure of the spring, as described
hereinabove, also enables various materials to be encapsulated
around the spring rather than merely removably mounting the spring
inside a casing.
All of the foregoing features and advantages are accomplished
through a simple and reliable manufacturing method, thereby
eliminating the usual complicated machining and assembly required
for other spring assemblies.
Although exemplary embodiments of the invention have been disclosed
and discussed, it will be understood that other applications of the
invention are possible and that these embodiments may be subjected
to various changes, modifications, and substitutions without
departing from the invention.
* * * * *